2-Octen-1-ylsuccinic anhydride, mixture of cis and trans

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

25 to 28 September 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

A category approach will be used for the hazard assessment of several endpoints. The hypothesis for the category of C8-12 Alkenyl Succinic Anhydrides is that data can be read-across among members of the category because their properties and behaviours are similar, based on common functional groups and similar breakdown products, and based on a constant pattern in changing of the potency of properties of the various carbon chain lengths. These features are in accordance with Annex XI, Section 1.5, of Regulation EC No. 1907/2006.  Common functional groups are: a dihydro-2,5 -Furandione (cyclic anhydride) ring, carbon chain of length 8 to 12 carbons, with or without branching alkyl groups, and a single carbon-carbon double bond in the carbon chain, location unspecified. There are no additional functional groups which would contribute incremental or different toxicity.
 
For each category member, the breakdown product is the dioic acid of the corresponding anhydride; these dioic acids also have common functional groups. A constant pattern may also be displayed in acute toxicity, dermal irritancy and biodegradation, with the lowest carbon chain length (C8) displaying the highest activity. Irritation, toxicity and degradation potential diminish with increasing carbon chain length. Read-across among the category members is substantiated by the common behaviour in physico-chemical and toxicity behaviours, as provided in the Chemical Category Report Format (CCRF) attached to the IUCLID file. It is adequate to fulfil the information requirements of Annex IX, to be the basis for classification and labelling decisions, and for risk assessment.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

sewage sludge

Radiolabelling:

no

Test temperature:

The adsorption of TPSA was evaluated using activated sludge at 20±0°C.

Analytical monitoring:

yes

Details on test conditions:

Adsorption Kinetics (Preliminary Test, Tier 1): The adsorption test was performed using duplicate samples of the activated sludge at sorbent (dry weight) to solution ratios of 1:100, 1:200 and 1:400. The activated sludge test samples were prepared using approximately 12.2, 6.1 and 3.05 g of sludge for the 1:100, 1:200 and 1:400 ratios, respectively. A 20 -mL aliquot of 0.01 M CaCl2 was added to each sludge sample and the sludge was equilibrated at least overnight prior to dosing with a 20 -mL aliquot of the 20 mg/L primary stock solution. In addition, two vessels were prepared as solid-less controls and two were blanks(no test substance). The solid-less controls permit correction for interaction between the test substance and the centrifuge tube (i.e., sorption to glass) or losses due to handling or degradation; the blank allows correction for background carbon and provides a matrix blank.
The test substance was added to the activated sludge/0.01 M CaCl2 in the test vessels and the test samples were shaken by hand for approximately 30
seconds immediately following dosing. The time zero samples were submitted for TOC analysis immediately following hand-shaking. Agitation at
approximately 150 rpm was started by placing the containers on their side on a Labline orbital shaker table (Model 8590) in an environmental chamber in the dark. Chamber temperature was set to 20 ± 2 °C and was monitored continuously with a minimum-maximum thermometer. Temperature extremes were
recorded daily on weekdays.
The test vessels were removed from the shaker for TOC analysis at various time intervals (e.g., 5 minutes and 3, 6 and 24 hours). At each interval the samples were centrifuged on a Beckman GS 6R at a setting of 1000 rpm for ten minutes to precipitate the solids. The supernatant was transferred to a separate glass
vessel and the volume was recorded. The supernatant was analyzed immediately for TOC. The blank controls were used to subtract the background carbon for each sample.
The percent adsorption was calculated at each time point, plotted versus time and the Kd and the KOC were calculated at equilibrium.
Mass Balance: During the testing, any losses of the test substance (i.e., onto the test vessels or otherwise) were determined. This was done simply by comparing the recovered total organic carbon concentrations in the solid-less controls, containing only 0.01 M CaCl2 and compared to the nominal concentration. 
Desorption Kinetics (Tier 2): The Tier 2 test consisted of a desorption kinetic experiment, which was a continuation of the adsorption experiments conducted in the Tier 1 test. 
The test solutions at a sludge-to-solution ratio of 1:400 from the Tier 1 test were used during Tier 2 testing. Based on the equilibration time determined from the Tier 1 test, sampling intervals for the Tier 2 test were set at time zero, 5 minutes and 3 and 6 hours. Each sample was analyzed for TOC in duplicate along
with two blank (i.e., sludge and 0.01 M CaCl2 only) and two solid‑less controls (i.e., 0.01M CaCl2 and test substance only) for the Tier 2 experiment.
Agitation during Tier 2 testing was conducted in the same manner as previously. The sludge and solution phases were separated; as much of the test solutionas was possible was removed from the test vessels, and the volume of solution measured and recorded for calculation of test substance carry-over.
To determine the desorption constant of the test substance, a volume of 0.01 M CaCl2 solution equal to the volume of aqueous phase removed after
centrifuging the adsorption phase solutions was added to each test vessel. The test substance was desorbed from the activated sludge by agitation for 24 hours. The suspension was centrifuged and the supernatant retained for analysis.
The percent desorption was calculated at each time point and the Kdes was calculated at equilibrium.

Sample No.:

#1

Duration:

6 h

Initial conc. measured:

6.4 other: aqueous TPSA concentrations (mg/L) of the solid-less controls

pH:

5.69

Sample No.:

#2

Duration:

6 h

Initial conc. measured:

6.4 other: aqueous TPSA concentrations (mg/L) of the solid-less controls

pH:

5.69

Sample no.:

#1

Duration:

6 h

Sample no.:

#2

Duration:

6 h

Type:

Koc

Value:

825

Temp.:

20 °C

Type:

log Koc

Value:

2.92

Temp.:

20 °C

Phase system:

other: Kdes

Type:

other: Kdes

Value:

0.087 L/kg

Phase system:

solids-water in activated sewage sludge

Type:

log Kp

Value:

2.38 L/kg

Remarks on result:

other: Reported as "Kd" value for activated sludge at 20 oC.

Adsorption and desorption constants:

Adsorption KOC for TPSA was determined to be 825 mL/g
Desorption Kdes for TPSA was determined to be 0.087 mL/g.

Recovery of test material:

Due to the nature of the test substance (e.g., rapid hydrolysis of parent compound), no chemical specific analytical measurements for the concentration of the test substance were performed. However, at each interval test samples were removed, centrifuged and supernatants analyzed for total organic carbon (TOC).

Transformation products:

not measured

Details on results (Batch equilibrium method):

Only the 1:400 sludge-to-solution ratio through the 6-hour interval is reported since equilibration was reached and also due to a high organic carbon background in all of the other sludge-to-solution ratios and at the 24-hour interval. The pH of the 0.01 M CaCl2 was 5.37. The pH of the 1:400 control sludge solution was 5.62 and the pH of the 1:400 test substance sludge solution was 5.69.
Adsorption Kinetics (Preliminary Test, Tier 1): The average measured concentration in the aqueous phase of the solid-less controls ranged from 6.09 to 6.64 mg C/L at time zero, 5 minutes and 3 and 6 hours and were near the measured nominal concentration of 6.4 mg C/L. Therefore, the test vessels were considered acceptable. Solid-less controls were used throughout the testing to correct for the minimal adsorption to test vessel walls.
Mean percent adsorption plateaued at the 3-hour interval and was determined to be 36.43% and 34.68% at 3 and 6 hours, respectively. The Kd value calculated at equilibrium (i.e., 6 hours) and the optimum sorbent to solution ratio (i.e., 1:400) was 238.33. The corresponding Koc value was 824.96.
Desorption Kinetics (Tier 2): The mean percent desorption value for activated sludge at equilibrium (6 hours) was 95.15%. The corresponding Kdes value was 0.087.

Statistics:

Statistical methods including means, standard deviations, and regression lines were used as appropriate. Bias will be effectively controlled through duplicate
sampling and replicate analysis.

Percent Adsorption and K_d Calculation: The percent of the test substance adsorbed was calculated for sludge as:

where: Ati		=		adsorption percentage at the time point ti(%)
		=		mass of test substance adsorbed on the sludge at time ti
m0		=		mass of test substance in the test tube at the beginning of the test (µg)

The adsorption coefficient (K_d) was calculated for sludge according to the following formula:

where:

C^adss(eq)		=		content of the substance adsorbed on sludge at adsorption equilibrium (µg/g)
C^adsaq(eq)		=		mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/mL); this concentration is analytically determined taking into account the values given by the blanks.
m^adss(eq)		=		mass of the test substance adsorbed on sludge at adsorption equilibrium (µg)
m^adsaq(eq)		=		mass of the test substance in the solution at adsorption equilibrium (µg)
msolid		=		quantity of the solid, expressed in dry mass of sludge (g)
V0		=		initial volume of the aqueous phase in contact with solid (mL)

 

Calculation of K_ocfrom K_d:The adsorption coefficient was expressed as a function of the organic carbon content of the sludge using the following equation:

where:

% OC

=

percent organic carbon of sludge (can be calculated by dividing the percent organic matter by 1.7,Black et al, 1965)

 

Desorption Calculations: Desorption is defined as the percentage of the test substance which isdesorbed, related to the quantity of substance previously adsorbed, under the test conditions:

where:

Dti	=	desorption percentage at the time point ti(%)
m^desaq(ti)	=	mass of test substance desorbed from the sludge at a time point ti(µg)
m^adss(eq)	=	mass of the test substance adsorbed on sludge at adsorption equilibrium (µg).

 

The desorption coefficient (K_des) is the ratio between the content of the substance remaining in the sludge phase and the mass concentration of the desorbed substance in the aqueous solution when desorption equilibrium is reached:

where:

Kdes	=	desorption coefficient (mL/g)
m^desaq(eq)	=	total mass of the test substance desorbed from sludge at desorption equilibrium (µg)
VT	=	total volume of the aqueous phase in contact with the sludge during the desorption kinetics test (mL).

Validity criteria fulfilled:

yes

Remarks:

Test temperature maintained at 20 ±2 °C.

Conclusions:

The adsorption of TPSA was evaluated using activated sludge at 20°C. The Kd, and Koc values for TPSA were determined at a sludge-to-solution ratio of 1:400 using data through 6 hours. The initial concentration of TSPA in the aqueous phase was 6.4 mg/L. The Kd and Koc values indicate that the test substance is moderately mobile (Koc <1000) and what adsorption there is, most likely is reversible considering the desorption values. The Kd value was reported as 238 mL/g, and the log Kd as 2.38 mL/g. The Koc was reported as 825 mL/g and the log Koc was reported as 2.92 mL/g. Data can be read-across among members of the C8-12 Alkenyl Succinic Anhydrides Category, based on common functional groups, similar break-down products and potency patterns among carbon-chain length. This is adequate to fulfil the information requirements, to be the basis for classification and labelling decisions, and for risk assessment.

Executive summary:

In the Study entitled “TPSA – Determining the Adsorption Coefficient (K_OC) Following OECD Guideline 106” (McLaughlin- Smithers Viscient, 2013), the adsorption coefficient of TPSA as a function of the organic carbon content of the activated sludge was determined. Activated sludge was selected for testing and was characterized for percent organic carbon. The percent adsorption, the adsorption coefficient (K_d) and the adsorption coefficient as a function of organic carbon (K_OC) were determined from adsorption experiments. The percent desorption and the desorption coefficient (K_des) were determined from the desorption kinetic experiments. Analysis of the test samples was performed by total organic carbon (TOC) analysis due to the rapid hydrolysis of the parent compound. The study was performed following the Smithers Viscient protocol entitled “TPSA – Determining the Adsorption Coefficient (K_OC) Following OECD Guideline 106” and was conducted to meet the requirements specified in OECD Guideline No. 106.

The adsorption of TPSA was evaluated using activated sludge at 20 ± 2°C. The K_d, and K_OC and values for TPSA were determined at a sludge-to-solution ratio of 1:400 using data through 6 hours. The initial concentration of TSPA in the aqueous phase was 6.4 mg/L. The K_d and K_OC values indicate that the test substance is moderately mobile (Koc <1000) and what adsorption there is, most likely is reversible considering the desorption values. The K_dand K_OC values for each sludge are summarized below:

Adsorption Tier 1 and 2
Sorbent to Solution Ratio	Hour	Mean Percent Adsorption (%)	Kd (mL/g)	Koc (mL/g)	Mean Percent Desorption (%)	Kdes (mL/g)
Activated Sludge
1:400	6	34.7	238	825	95.2	0.087

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 to 28 September 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

sewage sludge

Radiolabelling:

no

Test temperature:

The adsorption of TPSA was evaluated using activated sludge at 20±0°C.

Analytical monitoring:

yes

Details on test conditions:

Adsorption Kinetics (Preliminary Test, Tier 1): The adsorption test was performed using duplicate samples of the activated sludge at sorbent (dry weight) to solution ratios of 1:100, 1:200 and 1:400. The activated sludge test samples were prepared using approximately 12.2, 6.1 and 3.05 g of sludge for the 1:100, 1:200 and 1:400 ratios, respectively. A 20 -mL aliquot of 0.01 M CaCl2 was added to each sludge sample and the sludge was equilibrated at least overnight prior to dosing with a 20 -mL aliquot of the 20 mg/L primary stock solution. In addition, two vessels were prepared as solid-less controls and two were blanks(no test substance). The solid-less controls permit correction for interaction between the test substance and the centrifuge tube (i.e., sorption to glass) or losses due to handling or degradation; the blank allows correction for background carbon and provides a matrix blank.
The test substance was added to the activated sludge/0.01 M CaCl2 in the test vessels and the test samples were shaken by hand for approximately 30
seconds immediately following dosing. The time zero samples were submitted for TOC analysis immediately following hand-shaking. Agitation at
approximately 150 rpm was started by placing the containers on their side on a Labline orbital shaker table (Model 8590) in an environmental chamber in the dark. Chamber temperature was set to 20 ± 2 °C and was monitored continuously with a minimum-maximum thermometer. Temperature extremes were
recorded daily on weekdays.
The test vessels were removed from the shaker for TOC analysis at various time intervals (e.g., 5 minutes and 3, 6 and 24 hours). At each interval the samples were centrifuged on a Beckman GS 6R at a setting of 1000 rpm for ten minutes to precipitate the solids. The supernatant was transferred to a separate glass
vessel and the volume was recorded. The supernatant was analyzed immediately for TOC. The blank controls were used to subtract the background carbon for each sample.
The percent adsorption was calculated at each time point, plotted versus time and the Kd and the KOC were calculated at equilibrium.
Mass Balance: During the testing, any losses of the test substance (i.e., onto the test vessels or otherwise) were determined. This was done simply by comparing the recovered total organic carbon concentrations in the solid-less controls, containing only 0.01 M CaCl2 and compared to the nominal concentration. 
Desorption Kinetics (Tier 2): The Tier 2 test consisted of a desorption kinetic experiment, which was a continuation of the adsorption experiments conducted in the Tier 1 test. 
The test solutions at a sludge-to-solution ratio of 1:400 from the Tier 1 test were used during Tier 2 testing. Based on the equilibration time determined from the Tier 1 test, sampling intervals for the Tier 2 test were set at time zero, 5 minutes and 3 and 6 hours. Each sample was analyzed for TOC in duplicate along
with two blank (i.e., sludge and 0.01 M CaCl2 only) and two solid‑less controls (i.e., 0.01M CaCl2 and test substance only) for the Tier 2 experiment.
Agitation during Tier 2 testing was conducted in the same manner as previously. The sludge and solution phases were separated; as much of the test solutionas was possible was removed from the test vessels, and the volume of solution measured and recorded for calculation of test substance carry-over.
To determine the desorption constant of the test substance, a volume of 0.01 M CaCl2 solution equal to the volume of aqueous phase removed after
centrifuging the adsorption phase solutions was added to each test vessel. The test substance was desorbed from the activated sludge by agitation for 24 hours. The suspension was centrifuged and the supernatant retained for analysis.
The percent desorption was calculated at each time point and the Kdes was calculated at equilibrium.

Sample No.:

#1

Duration:

6 h

Initial conc. measured:

6.4 other: aqueous TPSA concentrations (mg/L) of the solid-less controls

pH:

5.69

Sample No.:

#2

Duration:

6 h

Initial conc. measured:

6.4 other: aqueous TPSA concentrations (mg/L) of the solid-less controls

pH:

5.69

Sample no.:

#1

Duration:

6 h

Sample no.:

#2

Duration:

6 h

Type:

Koc

Value:

825

Temp.:

20 °C

Type:

log Koc

Value:

2.92

Temp.:

20 °C

Phase system:

other: Kdes

Type:

other: Kdes

Value:

0.087 L/kg

Phase system:

solids-water in activated sewage sludge

Type:

log Kp

Value:

2.38 L/kg

Remarks on result:

other: Reported as "Kd" value for activated sludge at 20 oC.

Adsorption and desorption constants:

Adsorption KOC for TPSA was determined to be 825 mL/g
Desorption Kdes for TPSA was determined to be 0.087 mL/g.

Recovery of test material:

Due to the nature of the test substance (e.g., rapid hydrolysis of parent compound), no chemical specific analytical measurements for the concentration of the test substance were performed. However, at each interval test samples were removed, centrifuged and supernatants analyzed for total organic carbon (TOC).

Transformation products:

not measured

Details on results (Batch equilibrium method):

Only the 1:400 sludge-to-solution ratio through the 6-hour interval is reported since equilibration was reached and also due to a high organic carbon background in all of the other sludge-to-solution ratios and at the 24-hour interval. The pH of the 0.01 M CaCl2 was 5.37. The pH of the 1:400 control sludge solution was 5.62 and the pH of the 1:400 test substance sludge solution was 5.69.
Adsorption Kinetics (Preliminary Test, Tier 1): The average measured concentration in the aqueous phase of the solid-less controls ranged from 6.09 to 6.64 mg C/L at time zero, 5 minutes and 3 and 6 hours and were near the measured nominal concentration of 6.4 mg C/L. Therefore, the test vessels were considered acceptable. Solid-less controls were used throughout the testing to correct for the minimal adsorption to test vessel walls.
Mean percent adsorption plateaued at the 3-hour interval and was determined to be 36.43% and 34.68% at 3 and 6 hours, respectively. The Kd value calculated at equilibrium (i.e., 6 hours) and the optimum sorbent to solution ratio (i.e., 1:400) was 238.33. The corresponding Koc value was 824.96.
Desorption Kinetics (Tier 2): The mean percent desorption value for activated sludge at equilibrium (6 hours) was 95.15%. The corresponding Kdes value was 0.087.

Statistics:

Statistical methods including means, standard deviations, and regression lines were used as appropriate. Bias will be effectively controlled through duplicate
sampling and replicate analysis.

Percent Adsorption and K_d Calculation: The percent of the test substance adsorbed was calculated for sludge as:

where: Ati		=		adsorption percentage at the time point ti(%)
		=		mass of test substance adsorbed on the sludge at time ti
m0		=		mass of test substance in the test tube at the beginning of the test (µg)

The adsorption coefficient (K_d) was calculated for sludge according to the following formula:

where:

C^adss(eq)		=		content of the substance adsorbed on sludge at adsorption equilibrium (µg/g)
C^adsaq(eq)		=		mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/mL); this concentration is analytically determined taking into account the values given by the blanks.
m^adss(eq)		=		mass of the test substance adsorbed on sludge at adsorption equilibrium (µg)
m^adsaq(eq)		=		mass of the test substance in the solution at adsorption equilibrium (µg)
msolid		=		quantity of the solid, expressed in dry mass of sludge (g)
V0		=		initial volume of the aqueous phase in contact with solid (mL)

 

Calculation of K_ocfrom K_d:The adsorption coefficient was expressed as a function of the organic carbon content of the sludge using the following equation:

where:

% OC

=

percent organic carbon of sludge (can be calculated by dividing the percent organic matter by 1.7,Black et al, 1965)

 

Desorption Calculations: Desorption is defined as the percentage of the test substance which isdesorbed, related to the quantity of substance previously adsorbed, under the test conditions:

where:

Dti	=	desorption percentage at the time point ti(%)
m^desaq(ti)	=	mass of test substance desorbed from the sludge at a time point ti(µg)
m^adss(eq)	=	mass of the test substance adsorbed on sludge at adsorption equilibrium (µg).

 

The desorption coefficient (K_des) is the ratio between the content of the substance remaining in the sludge phase and the mass concentration of the desorbed substance in the aqueous solution when desorption equilibrium is reached:

where:

Kdes	=	desorption coefficient (mL/g)
m^desaq(eq)	=	total mass of the test substance desorbed from sludge at desorption equilibrium (µg)
VT	=	total volume of the aqueous phase in contact with the sludge during the desorption kinetics test (mL).

Validity criteria fulfilled:

yes

Remarks:

Test temperature maintained at 20 ±2 °C.

Conclusions:

The adsorption of TPSA was evaluated using activated sludge at 20°C. The Kd, and Koc values for TPSA were determined at a sludge-to-solution ratio of 1:400 using data through 6 hours. The initial concentration of TSPA in the aqueous phase was 6.4 mg/L. The Kd and Koc values indicate that the test substance is moderately mobile (Koc <1000) and what adsorption there is, most likely is reversible considering the desorption values. The Kd value was reported as 238 mL/g, and the log Kd as 2.38 mL/g. The Koc was reported as 825 mL/g and the log Koc was reported as 2.92 mL/g. Data can be read-across among members of the C8-12 Alkenyl Succinic Anhydrides Category, based on common functional groups, similar break-down products and potency patterns among carbon-chain length. This is adequate to fulfil the information requirements, to be the basis for classification and labelling decisions, and for risk assessment.

Executive summary:

In the Study entitled “TPSA – Determining the Adsorption Coefficient (K_OC) Following OECD Guideline 106” (McLaughlin- Smithers Viscient, 2013), the adsorption coefficient of TPSA as a function of the organic carbon content of the activated sludge was determined. Activated sludge was selected for testing and was characterized for percent organic carbon. The percent adsorption, the adsorption coefficient (K_d) and the adsorption coefficient as a function of organic carbon (K_OC) were determined from adsorption experiments. The percent desorption and the desorption coefficient (K_des) were determined from the desorption kinetic experiments. Analysis of the test samples was performed by total organic carbon (TOC) analysis due to the rapid hydrolysis of the parent compound. The study was performed following the Smithers Viscient protocol entitled “TPSA – Determining the Adsorption Coefficient (K_OC) Following OECD Guideline 106” and was conducted to meet the requirements specified in OECD Guideline No. 106.

The adsorption of TPSA was evaluated using activated sludge at 20 ± 2°C. The K_d, and K_OC and values for TPSA were determined at a sludge-to-solution ratio of 1:400 using data through 6 hours. The initial concentration of TSPA in the aqueous phase was 6.4 mg/L. The K_d and K_OC values indicate that the test substance is moderately mobile (Koc <1000) and what adsorption there is, most likely is reversible considering the desorption values. The K_dand K_OC values for each sludge are summarized below:

Adsorption Tier 1 and 2
Sorbent to Solution Ratio	Hour	Mean Percent Adsorption (%)	Kd (mL/g)	Koc (mL/g)	Mean Percent Desorption (%)	Kdes (mL/g)
Activated Sludge
1:400	6	34.7	238	825	95.2	0.087

Description of key information

The adsorption coefficient of tetrapropenyl succinic anhydride was determined on activated sludge by the batch equilibrium method in accordance with OECD Guideline 106, by read-across based on a grouping of substances (category approach). 

Key value for chemical safety assessment

Koc at 20 °C:

825

Additional information

The key value for the adsorption coefficient of the substance is the experimentally-determined value for tetrapropenyl succinic anhydride, by read-across based on a grouping of substances (category approach).

The adsorption coefficient of tetrapropenyl succinic anhydride was determined as a function of the organic carbon content of the activated sludge. Activated sludge was selected for testing and was characterized for percent organic carbon. The percent adsorption, the adsorption coefficient (K_d) and the adsorption coefficient as a function of organic carbon (K_OC) were determined from adsorption experiments. The percent desorption and the desorption coefficient (K_des) were determined from the desorption kinetic experiments. Analysis of the test samples was performed by total organic carbon (TOC) analysis due to the rapid hydrolysis of the parent compound. The study was performed following the laboratory protocol entitled “TPSA – Determining the Adsorption Coefficient (K_OC) Following OECD Guideline 106” and was conducted to meet the requirements specified in OECD Guideline No. 106.

 

The adsorption of tetrapropenyl succinic anhydride was evaluated using activated sludge at 20 ± 2°C. The K_d, and K_OC and values for the test substance were determined at a sludge-to-solution ratio of 1:400 using data through 6 hours. The initial concentration of the test substance in the aqueous phase was 6.4 mg/L. The K_d and K_OCvalues indicate that the test substance is moderately mobile (K_oc<1000) and what adsorption there is, most likely is reversible considering the desorption values. The K_oc for tetrapropenyl succinic anhydride was reported as K_oc= 825 L/kg, or log K_oc= 2.916, and were selected as the key values by read-across based on a grouping of substances (category approach). 

A category approach is used for the hazard assessment of several endpoints. The hypothesis for the category of C8-12 Alkenyl Succinic Anhydrides is that data can be read-across among members of the category, because the properties and behaviours of category members are similar, based on common functional groups, similar breakdown products, and demonstration of a constant pattern associating the potency of properties with the various carbon chain lengths. Functional groups include a dihydro-2,5-furandione cyclic anhydride ring, a carbon chain of length 8 -12 carbons, and a single carbon-carbon double-bond within the carbon chain. The primary functional group associated with toxicity is the succinic anhydride moiety, which is quickly hydrolysed to form a butanedioic acid. A constant pattern may also be displayed in acute toxicity, dermal irritancy and biodegradation, with the lowest carbon chain length (C8) displaying the highest activity. Irritation, toxicity and degradation potential diminish with increasing carbon chain length. Read-across among the category members is substantiated by the common behaviour in physico-chemical and toxicity behaviours, as provided in the Chemical Category Report Format (CCRF) attached to the IUCLID file. It is adequate to fulfil the information requirements of Annex IX, to be the basis for classification and labelling decisions, and for risk assessment.

[LogKoc: 2.916]